Each Christmas elf makes $x$ toys in an hour. $n$ elves work for $t$ hours to produce $1000$ toys. Write an equation that relates $x$, $n$, and $t$.
Let's look at the number of toys a single elf makes. A single elf makes $x$ toys every hour and works $t$ hours. So in total, the elf makes $x\cdot t$ toys: $\begin{aligned} &\phantom{=}\left(x\,\dfrac{\text{toys}}{\text{hour}}\right)\left(t\,\text{hours}\right) \\\\ &=x\cdot t\,\dfrac{\text{toys}}{\cancel\text{hour}}\cdot\,\cancel\text{hours} \\\\ &=x\cdot t\,\text{toys} \end{aligned}$ Since there are $n$ elves, the total number of toys, $1000$, is equal to $n\cdot x\cdot t$ : $n\cdot x\cdot t=1000$